LAB12 BCD substrator (BCD減法器 10的補數方式)

LAB12 BCD substrator (BCD減法器 10的補數方式)

LAB10 BCD substrator (BCD減法器) 適用於DE2-70
a - b - bor_in  = {bor_out , diff_out}
0-0=0 , 9-0=9 , 0-9=-9

SW[7:4] 被減數  輸入
SW[3:0] 減數 輸入
HEX0 差  輸出
LEDG[0] 借位  輸出

//------------------------------------

//4-bit BCD substrator  10's Complement 

//Filename : BCD_substrator.v

//------------------------------------

module BCD_10s_comp (SW, LEDR, LEDG , CLOCK_27 ,KEY ,HEX0 ,HEX1 ,HEX2,HEX3 );

 input  [17:0] SW;    // toggle switches

 input  [7:0] KEY;       // Push bottom

 input  CLOCK_27;     //Clock 27MHz , 50Mhz

 output [17:0]LEDR;    // red  LEDS   

 output [8:0] LEDG;    // green LEDs

    

 output [6:0] HEX0,HEX1,HEX2,HEX3; //7-segment display

    

  

 //(Diff , Bor_out, Bor_in, A, B);

 //output Diff [3:0] S;  //Difference output

 //output Bor_out;    //Borrow out

 //input Bor_in;       //Borrow in

 //input [3:0] A, B;  //Input data  minuend /  subtrahend  A-B

 // A-B-Bor_in = Diff , Bor_out

   

    wire [3:0] A,B;   //Input data  minuend /  subtrahend  A-B

    wire [3:0] Diff_tmp;  //Difference output

    wire Bor_out;       //Carry out

    wire [7:0] segout0;   //HEX 0

    assign  A=SW[7:4] ;  //minuend A      

    assign  B=SW[3:0] ;  //subtrahend  B

    assign  LEDR[7:0]=SW[7:0];

    assign  LEDR[17]=SW[17];

    

    reg [3:0] A_tmp,B_tmp1;

    wire [3:0] S_tmp,B_tmp;

wire C4;

reg  [3:0] A_mod,B_mod;

    always @ ( A or B  )

begin

if (A<10)

A_tmp = A;   //若是>9 則為9

else

A_tmp =4'b1001;

  

if (B<10)

B_tmp1 = B;  //若是>9 則為9

else

B_tmp1 =4'b1001;

  

end

 

adder4 U0 (.S(B_tmp), 

.Cout(), 

.A(4'b1010) , 

.B(~B_tmp1), 

.Cin(1'b1));

BCD_4bit_FA U1( .S1(S_tmp),

.Cout1(C4),

.Cin1(1'b0), 

.A1(A_tmp), 

.B1(B_tmp));

    assign Bor_out = ~C4;    

    always @ ( A_tmp or B_tmp or C4 or S_tmp )

begin

        case (Bor_out)

1 : begin 

B_mod = ~S_tmp; //Modified code

A_mod = 4'b1010;

end

0:  begin

B_mod = S_tmp;

A_mod = 4'b0000;

end

endcase

end

adder4 U2 ( .S(Diff_tmp),

.Cout(),

.A(A_mod), 

.B(B_mod),

.Cin(Bor_out));

  

   assign LEDG[0]=Bor_out;

   

_7seg UUT0(.hex((Diff_tmp)),

               .seg(segout0));

    

    assign HEX0=segout0[6:0];

    

   

    assign HEX1=7'b111_1111;

assign HEX2=7'b111_1111;

    assign HEX3=7'b111_1111;

    

endmodule

//******************************************************

 module BCD_4bit_FA ( S1, Cout1, Cin1, A1, B1);

 output [3:0] S1; //Sumation output

 output Cout1;    //Carry out

 input Cin1;      //Carry in

 input [3:0] A1, B1;//Input data

 wire [3:0] A_tmp11,B_tmp11,S_tmp11;

 wire C41;

 reg [3:0] B_mod11;

 reg F1;

 //4-bit binary adder

 adder4 BINADD(

            .S(S_tmp11),

            .Cout(C41),

            .Cin(Cin1),

            .A(A1),

            .B(B1)

           );

 //Modify binary code with '0110'

 adder4 MODADD(

            .S(S1),

            .Cout(),

            .Cin(1'b0),

            .A(S_tmp11),

            .B(B_mod11)

           );

 always @ (Cin1 or A1 or B1 or C41 or S_tmp11)

 begin

 //F=C4+S3(S2+S1)

  F1 = (C41 | (S_tmp11[3] & (S_tmp11[2] | S_tmp11[1])));

  B_mod11 = {1'b0, F1, F1, 1'b0}; //Modified code

 end

 assign Cout1 = F1;

 endmodule

//----------------------

//4-bit unsigned adder

//Filename : adder4.v

//----------------------                                                                                                                                                                                                                   

module adder4(S, Cout, A, B, Cin);

 output [3:0] S;   //4-bit sum

 output Cout;    //Carry out

 input [3:0] A, B; //Inputs

 input Cin;    //Carry in

 //Assign the sum of (A+B+Cin) to Cout and Sum

 assign {Cout, S} = A + B + Cin;

endmodule

//-----------------------------------------

//Common-cathod seven segment display

//using case.....endcase statement

//Filename : sevenseg_case.v

//----------------------------------------- 

module _7seg(hex , seg);

    input  [3:0] hex;

    output [7:0] seg;

    reg    [7:0] seg;

    

        

 // segment encoding

 //      0

 //     ---  

 //  5 |   | 1

 //     ---   <- 6

 //  4 |   | 2

 //     ---

 //      3

 always @(hex)

 begin

  case (hex)

       // Dot point is always disable

       4'b0001 : seg = 8'b11111001;   //1 = F9H

       4'b0010 : seg = 8'b10100100;   //2 = A4H

       4'b0011 : seg = 8'b10110000;   //3 = B0H

       4'b0100 : seg = 8'b10011001;   //4 = 99H

       4'b0101 : seg = 8'b10010010;   //5 = 92H

       4'b0110 : seg = 8'b10000010;   //6 = 82H

       4'b0111 : seg = 8'b11111000;   //7 = F8H

       4'b1000 : seg = 8'b10000000;   //8 = 80H

       4'b1001 : seg = 8'b10010000;   //9 = 90H

       4'b1010 : seg = 8'b10001000;   //A = 88H

       4'b1011 : seg = 8'b10000011;   //b = 83H

       4'b1100 : seg = 8'b11000110;   //C = C6H

       4'b1101 : seg = 8'b10100001;   //d = A1H

       4'b1110 : seg = 8'b10000110;   //E = 86H

       4'b1111 : seg = 8'b10001110;   //F = 8EH

       default : seg = 8'b11000000;   //0 = C0H

     endcase

   end

   

endmodule